Electronic Project Engineer's Best Partner!

X****Liu country

Ask and Answer

Adding CCFL light or LED backlight to a 6 digit/ 7 segment LCD display

1228 1 Mar 18.2020, 18:07:14
Hello, Is possible to add CCFL light or LED backlight to a 6 digit/7 segment LCD display which has no backlight from the beginning? I have seen some article about doing that many years ago (could not find now...) by removing the reflective shield layer from the backside , not sure if I should separate that shield from a possible layer (polarization ?) between it and the LCD glass or other consideration that I should be aware off. ATtached 2 images from the LCD display Many thanks in advance!.

How about removing solder mask from PCB?

1279 1 Mar 17.2020, 18:14:19
All: I have some 1.5” Square Boards PCB’s which I want to strip all the solder mask off. Has anyone tried using this solvent for stripping solder makes. If the results were horrid, I would like to know.

How to make a dummy load for testing?

1266 1 Mar 15.2020, 01:46:22
I'm currently working on a battery supply with protection/charging and I would like to test battery discharge but right now I only have LEDs as a load and current use is low so discharge is too slow. I tried adding more LEDs but it seems like the circuit cuts off for some reason. Is there a better way to have a manageable load that I could adjust or calculate to drain my battery at an acceptable rate? I'm using a li-ion 18650 3300mah. Thanks

How to Make LED Flasher Circuit?

1447 1 Mar 13.2020, 02:10:00
Hi,Can someone guide me how to design LED Flasher using BD139 which all the LEDs (max 8 LEDs) must connected in series? What i have found in the net is the LEDs connected in parallel. See attachment.

The question about PCBA for USB-C receptacle.

1347 1 Mar 11.2020, 21:18:30
Hi, I have a small USB-C. It has 4 main legs which should be soldered (I think), however the length is of such that they don't come close to clearing a 0.8mm PCB thickness. On the attached pictures you can see I've hand soldered them and the solder has sunk. Can it work if the legs of USB-C were solder pasted with PCBA? Wondering what the process is!

Will we get component tombstoning of this resistor and capacitor?

1225 1 Feb 28.2020, 19:20:51
Hi, Please advise if we will get “tombstoning” if we remove the thermal reliefs to the pads of the following components.. The component ringed in yellow is an 1812 ceramic capacitor. The component ringed in red is a 2010 chip resistor.We want to simply merge the left hand pads of these components completely into the surrounding thermal copper pour. (for better cooling of the components). However, as you can see, the right hand pads of these components have less copper attached to them. If we merge the left hand pads completely into the thermal copper pours, then will the right hand pads heat up more during the SMT soldering process, resulting in the components tombstoning?

Confused about creating SMD capacitor footprint libraries

1184 1 Feb 25.2020, 22:43:08
How should I decide on which footprint for chip capacitors to use? Should I create a separate footprint for caps from each manufacturer (and each of their dimensional tolerances)? I have so little experience with commercial board assembly that I see a multitude of answers, which I've tried to outline below. I'm having some expensive boards assembled (down to 0201 and 0.4mm PQFN pitches...., with "HDI" technology). I don't want them to be screwed up. Do people normally use a footprint generator to calculate the pad sizes, or go by the manufacturer recommended footprints? Or should I ask the assembly company to tell me what pad sizes to use? Or do people not normally worry about it, as they swap between brands of passives quite often, so there is no point designing for a particular model? Though, there are some like with epoxy terminals which are much more variable than the run-of-the-mill parts. Using Murata 0402, 0.5mm height, using "nominal" dimensions as an example, I see that there...

From Gerbers to Schematic?

1017 1 Feb 24.2020, 22:17:31
I designed a board in Sprint-Layout some years ago, back when I first started designing my own PCBs. It has gotten more and more complicated as I had revisions and improvements, and is now a 4 layer PCB of 150x200mm in size. None of this was done with schematics at all, just adding components and tying it into the circuitry as it needed to be.At this point, I would like to refine the design and have a regular schematic so I can completely re-work the PCB layout w/o starting from complete scratch of the now complicated circuitry. In essence, I need to reverse-engineer my own work!Since Sprint-Layout doesnt deal with netlists or schematics, just simply drawing circuits, is there a way to use the gerber files Sprint-Layout generates in Eagle/KiCad (2 programs I use now) or another to create a schematic?

Single button start-shutdown in MCP1640 circuit with modes

978 1 Feb 22.2020, 00:43:49
I am trying to modify this circuit incorporating a n.o. pushbutton to power it on and off, and to have different modes depending on how long the pushputton is pressed. I would like to use an Attiny13 to control the logic for the modes and control the on-off but I am new to circuit design and wondering if anyone could help.

How to choose PCB material?

972 1 Feb 20.2020, 22:23:14
Which PCB material is best for your electronic project?